Snap is an easy to use interactive selection tool designed to extract solid or opaque objects. It does not affect the foreground in any way and transfers it's selection directly into a Photoshop selection. On the other hand, EZ Mask is an easy to use interactive image masking tool capable of extracting almost any object in an image--even if you are dealing with fine hair detail, smoke, reflections or transparency. In addition, the foreground colors are estimated in the semi-transparent areas which is invaluable in creating a seamless composite.